The Motif imake-configuration files are part of the LynxOS X Window
package. They must be copied to the /usr/X11R6 directory tree.

cp /usr/lib/X11/config/Motif.* /usr/X11R6/lib/X11/config

5.2. Motif library patch for LynxOS x86 2.3.0

The XFree86 libraries are compiled with the -mposix compiler option
while the Motif libraries shipped with LynxOS x86 2.3.0 are not. This
incompatibility will cause Motif XmFileSelection widgets to be linked
with the wrong (i.e. POSIX) directory routines. To circumvent this
problem apply the following patch to the library: